Elasticsearch rails/Elasticsearch模型搜索模型关联

我有一个名为的模型Movie,如下所示:

class Movie < ActiveRecord::Base
  include Elasticsearch::Model
  include Elasticsearch::Model::Callbacks

  has_many :actors, after_add: [ lambda {|a,c| a.__elasticsearch__.index_document}],
                    after_remove: [ lambda {|a,c| a.__elasticsearch__.index_document}]

  settings index: {number_of_shards: 1} do
    mappings dynamic: 'false' do
      indexes :title, analyzer: 'snowball', boost: 100
      indexes :actors
    end
  end

   def as_indexed_json(options={})
    self.as_json(
      include: {
          actors: { only: :name}
      }
    )
  end
end

当我这样做时Movie.first.as_indexed_json,我得到:

{"id"=>6, "title"=>"Back to the Future ", 
"created_at"=>Wed, 03 Dec 2014 22:21:24 UTC +00:00, 
"updated_at"=>Fri, 12 Dec 2014 23:40:03 UTC +00:00, 
"actors"=>[{"name"=>"Michael J Fox"}, {"name"=>"Christopher Lloyd"}, 
{"name"=>"Lea Thompson"}]}

但是当我Movie.search("Christopher Lloyd").records.first得到时:=> nil.

我可以对索引进行哪些更改来搜索与搜索到的actor相关联的电影？